H. SKEY.—Smokeless and Self-feeding Furnace. 25 
vessel on the ways. To replace a vessel on the cradle, the operation is merely 
the reverse of that just described. 
The time occupied in raising a vessel after it is once fixed securely on the 
carriage is, in the case of small vessels, about twenty minutes, when the 
hauling-up chain is worked single. With a large vessel the speed is found 
to be about 15 ft. or 16 ft. per minute. In this case the chain is used double. 
Dolphins, consisting of clusters of five piles, are placed in convenient 
positions for steadying a vessel going on the slip. At present only three of 
the dolphins are completed, but three more are to be erected. The piles used 
for these dolphins are of the jarrah wood of South Australia, which is believed 
to resist the worm for an unlimited period. 
Art. IV.—On a Smokeless and Self-feeding Furnace for Lignites and other 
Fuels, and the Utilization of the Waste Heat. Ву H. Зкеү. 
(PL V.) 
[Read before the Otago Institute, 12th August, 1873.1 
Ат a time when the material wealth. of nations is recognised as being so 
intimately associated with those immense stores of power obtainable from the 
fuels occurring in the carboniferous deposits of past ages, any apology for 
treating on the economie consumption of these fuels would be superfluous. 
It is evident that when fuel, of whatever kind, is consumed in such a 
manner that there is no smoke evolved, and no cinders and unoxidized 
portions of the fuel left among the ash, then the theoretical conditions leading 
to the evolution of all the heat force are present, so far as the furnace itself is 
concerned ; while it belongs to the external arrangements, such as form of 
boiler and flues, and perfection of engine employed, to determine how much of 
this force is actually available, or, in other words, how much duty can be 
obtained from a given weight of fuel. 
Judging of the evaporating power of fuels by the amount of their fixed 
carbon, their analyses show that the combustion of 1:5 tons of Green Island or 
Clutha coal should produce the same amount of steam as one ton of N ewcastle 
coal If we take one ton of Newcastle coal and consume it ina given time 
—say twenty-four hours—in an ordinary furnace specially adapted for the 
combustion of this and other coals that coke and can be stirred, and then, in 
- the same furnace, attempt the combustion of the equivalent 1-5 tons of Green 
Island coal in the same time, failure would be the probable result. For, in the 
first place, the bottom of the fire and fire-bars would soon be covered with an 
D 
